Phase II trial of AKT inhibitor MK-2206 in patients with advanced breast cancer who have tumors with PIK3CA or AKT mutations, and/or PTEN loss/PTEN mutation.

BACKGROUND: The PI3K/AKT pathway is activated through PIK3CA or AKT1 mutations and PTEN loss in breast cancer. We conducted a phase II trial with an allosteric AKT inhibitor MK-2206 in patients with advanced breast cancer who had tumors with PIK3CA/AKT1 mutations and/or PTEN loss/mutation. METHODS: The primary endpoint was objective response rate (ORR). Secondary endpoints were 6-month progression-free survival (6 m PFS), predictive and pharmacodynamic markers, safety, and tolerability. Patients had pre-treatment and on-treatment biopsies as well as collection of peripheral blood mononuclear cells (PBMC) and platelet-rich plasma (PRP). Next-generation sequencing, immunohistochemistry, and reverse phase protein arrays (RPPA) were performed. RESULTS: Twenty-seven patients received MK-2206. Eighteen patients were enrolled into the PIK3CA/AKT1 mutation arm (cohort A): 13 had PIK3CA mutations, four had AKT1 mutations, and one had a PIK3CA mutation as well as PTEN loss. ORR and 6 m PFS were both 5.6% (1/18), with one patient with HR+ breast cancer and a PIK3CA E542K mutation experiencing a partial response (on treatment for 36 weeks). Nine patients were enrolled on the PTEN loss/mutation arm (cohort B). ORR was 0% and 6 m PFS was 11% (1/9), observed in a patient with triple-negative breast cancer and PTEN loss. The study was stopped early due to futility. The most common adverse events were fatigue (48%) and rash (44%). On pre-treatment biopsy, PIK3CA and AKT1 mutation status was concordant with archival tissue testing. However, two patients with PTEN loss based on archival testing had PTEN expression on the pre-treatment biopsy. MK-2206 treatment was associated with a significant decline in pAKT S473 and pAKT T308 and PI3K activation score in PBMC and PRPs, but not in tumor biopsies. By IHC, there was no significant decrease in median pAKT S473 or Ki-67 staining, but a drop was observed in both responders. CONCLUSIONS: MK-2206 monotherapy had limited clinical activity in advanced breast cancer patients selected for PIK3CA/AKT1 or PTEN mutations or PTEN loss. This may, in part, be due to inadequate target inhibition at tolerable doses in heavily pre-treated patients with pathway activation, as well as tumor heterogeneity and evolution in markers such as PTEN conferring challenges in patient selection. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01277757 . Registered 13 January 2011.

Ph-like acute lymphoblastic leukemia: a high-risk subtype in adults.

Philadelphia chromosome (Ph)-like acute lymphoblastic leukemia (ALL) is a high-risk subtype of ALL in children. There are conflicting data on the incidence and prognosis of Ph-like ALL in adults. Patients with newly diagnosed B-cell ALL (B-ALL) who received frontline chemotherapy at MD Anderson Cancer Center underwent gene expression profiling of leukemic cells. Of 148 patients, 33.1% had Ph-like, 31.1% had Ph+, and 35.8% had other B-ALL subtypes (B-other). Within the Ph-like ALL cohort, 61% had cytokine receptor-like factor 2 (CRLF2) overexpression. Patients with Ph-like ALL had significantly worse overall survival (OS), and event-free survival compared with B-other with a 5-year survival of 23% (vs 59% for B-other, P = .006). Sixty-eight percent of patients with Ph-like ALL were of Hispanic ethnicity. The following were associated with inferior OS on multivariable analysis: age (hazard ratio [HR], 3.299; P < .001), white blood cell count (HR, 1.910; P = .017), platelet count (HR, 7.437; P = .005), and Ph-like ALL (HR, 1.818; P = .03). Next-generation sequencing of the CRLF2+ group identified mutations in the JAK-STAT and Ras pathway in 85% of patients, and 20% had a CRLF2 mutation. Within the CRLF2+ group, JAK2 mutation was associated with inferior outcomes. Our findings show high frequency of Ph-like ALL in adults, an increased frequency of Ph-like ALL in adults of Hispanic ethnicity, significantly inferior outcomes of adult patients with Ph-like ALL, and significantly worse outcomes in the CRLF2+ subset of Ph-like ALL. Novel strategies are needed to improve the outcome of these patients.

Variants with a low allele frequency detected in genomic DNA affect the accuracy of mutation detection in cell-free DNA by next-generation sequencing.

BACKGROUND: Next-generation sequencing of cell-free DNA (cfDNA) has been shown to be a useful noninvasive test for detecting mutations in solid tumors. METHODS: Targeted gene sequencing was performed with a panel of 263 cancer-related genes for cfDNA and genomic DNA of peripheral blood mononuclear cells (PBMCs) obtained from presurgical specimens of 6 lung cancer patients, and mutation calls in these samples were compared with those of primary tumors and corresponding patient-derived xenografts (PDXs). RESULTS: Approximately 67% of the mutations detected in the tumor samples (primary tumors and/or PDXs) were also detected in genomic DNA from PBMCs as background mutations. These background mutations consisted of germline polymorphisms and a group of mutations with low allele frequencies, mostly <10%. These variants with a low allele frequency were repeatedly detected in all types of samples from the same patients and at similarly low allele frequency levels in PBMCs from different patients; this indicated that their detection might be derived from common causes, such as homologous sequences in the human genome. Allele frequencies of mutations detected in both primary tumors and cfDNA showed 2 patterns: 1) low allele frequencies (approximately 1%-10%) in cfDNA but high allele frequencies (usually >10% or >3-fold increase) in primary tumors and further enrichment in PDXs and 2) similar allele frequencies across samples. CONCLUSIONS: Because only a small fraction of total cfDNA might be derived from tumor cells, only mutations with the first allele frequency pattern may be regarded as tumor-specific mutations in cfDNA. Effective filtering of background mutations will be required to improve the accuracy of mutation calls in cfDNA. Cancer 2018;124:1061-9. © 2017 American Cancer Society.

Metachronous Medulloblastoma in a Child With Successfully Treated Neuroblastoma: Case Report and Novel Findings of DNA Sequencing.

Metachronous neoplasms have rarely been reported in patients with neuroblastoma. This report presents the clinical case of a 23-month-old child who was diagnosed with an anaplastic medulloblastoma 5 months after completing treatment for stage IV neuroblastoma. The patient was treated with complete surgical resection and adjuvant chemoradiation followed by maintenance chemotherapy at an outside institution and came to our institution for further management. A pathologic diagnosis and review of both the suprarenal and posterior fossa masses were performed, as well as a genetic analysis of both cerebellar tumor tissue and blood using next-generation gene sequencing. At our institution, the patient was submitted to induction chemotherapy followed by high-dose chemotherapy and autologous stem cell transplantation and remains free of disease 2 years after completion of treatment. Genetic analysis revealed multiple somatic copy number variations with most deleted genes located in 2q37, a region which harbors genes involved in epigenetic regulation and tumor suppression. A homozygous deletion was found in the TSC2 gene, which is a clinically actionable gene, and patients with activating deletions in TSC2 can potentially be eligible for basket clinical trials with mTOR inhibitors. Germline single nucleotide variants were also identified in multiple genes involved in cancer (ALK, FGFR3, FLT3/4, HNF1A, NCOR1, and NOTCH2/3), cancer predisposition (TP53, TSC1, and BRCA1/2), and genes involved in DNA repair (MSH6, PMS2, POLE, and ATM). Metachronous neoplasms are rare and challenging to treat, hence genetic analysis and referral are needed to exclude hereditary cause. DNA sequencing of the tumor and germline can help identify alterations that increase predisposition or can be used to guide treatment decisions on recurrence and when standard options fail.

Bias from removing read duplication in ultra-deep sequencing experiments.

MOTIVATION: Identifying subclonal mutations and their implications requires accurate estimation of mutant allele fractions from possibly duplicated sequencing reads. Removing duplicate reads assumes that polymerase chain reaction amplification from library constructions is the primary source. The alternative-sampling coincidence from DNA fragmentation-has not been systematically investigated. RESULTS: With sufficiently high-sequencing depth, sampling-induced read duplication is non-negligible, and removing duplicate reads can overcorrect read counts, causing systemic biases in variant allele fraction and copy number variation estimations. Minimal overcorrection occurs when duplicate reads are identified accounting for their mate reads, inserts are of a variety of lengths and samples are sequenced in separate batches. We investigate sampling-induced read duplication in deep sequencing data with 500× to 2000× duplicates-removed sequence coverage. We provide a quantitative solution to overcorrection and guidance for effective designs of deep sequencing platforms that facilitate accurate estimation of variant allele fraction and copy number variation. AVAILABILITY AND IMPLEMENTATION: A Python implementation is freely available at https://bitbucket.org/wanding/duprecover/overview CONTACT: : wzhou1@mdanderson.org, kchen3@mdanderson.org Supplementary information: Supplementary data are available at Bioinformatics online.

Clinical actionability enhanced through deep targeted sequencing of solid tumors.

BACKGROUND: Further advances of targeted cancer therapy require comprehensive in-depth profiling of somatic mutations that are present in subpopulations of tumor cells in a clinical tumor sample. However, it is unclear to what extent such intratumor heterogeneity is present and whether it may affect clinical decision-making. To study this question, we established a deep targeted sequencing platform to identify potentially actionable DNA alterations in tumor samples. METHODS: We assayed 515 formalin-fixed paraffin-embedded (FFPE) tumor samples and matched germline DNA (475 patients) from 11 disease sites by capturing and sequencing all the exons in 201 cancer-related genes. Mutations, indels, and copy number data were reported. RESULTS: We obtained a 1000-fold mean sequencing depth and identified 4794 nonsynonymous mutations in the samples analyzed, of which 15.2% were present at <10% allele frequency. Most of these low level mutations occurred at known oncogenic hotspots and are likely functional. Identifying low level mutations improved identification of mutations in actionable genes in 118 (24.84%) patients, among which 47 (9.8%) otherwise would have been unactionable. In addition, acquiring ultrahigh depth also ensured a low false discovery rate (<2.2%) from FFPE samples. CONCLUSIONS: Our results were as accurate as a commercially available CLIA-compliant hotspot panel but allowed the detection of a higher number of mutations in actionable genes. Our study reveals the critical importance of acquiring and utilizing high sequencing depth in profiling clinical tumor samples and presents a very useful platform for implementing routine sequencing in a cancer care institution.

Extend the benchmarking indel set by manual review using the individual cell line sequencing data from the Sequencing Quality Control 2 (SEQC2) project.

Accurate indel calling plays an important role in precision medicine. A benchmarking indel set is essential for thoroughly evaluating the indel calling performance of bioinformatics pipelines. A reference sample with a set of known-positive variants was developed in the FDA-led Sequencing Quality Control Phase 2 (SEQC2) project, but the known indels in the known-positive set were limited. This project sought to provide an enriched set of known indels that would be more translationally relevant by focusing on additional cancer related regions. A thorough manual review process completed by 42 reviewers, two advisors, and a judging panel of three researchers significantly enriched the known indel set by an additional 516 indels. The extended benchmarking indel set has a large range of variant allele frequencies (VAFs), with 87% of them having a VAF below 20% in reference Sample A. The reference Sample A and the indel set can be used for comprehensive benchmarking of indel calling across a wider range of VAF values in the lower range. Indel length was also variable, but the majority were under 10 base pairs (bps). Most of the indels were within coding regions, with the remainder in the gene regulatory regions. Although high confidence can be derived from the robust study design and meticulous human review, this extensive indel set has not undergone orthogonal validation. The extended benchmarking indel set, along with the indels in the previously published known-positive set, was the truth set used to benchmark indel calling pipelines in a community challenge hosted on the precisionFDA platform. This benchmarking indel set and reference samples can be utilized for a comprehensive evaluation of indel calling pipelines. Additionally, the insights and solutions obtained during the manual review process can aid in improving the performance of these pipelines.

Role for the nuclear receptor-binding SET domain protein 1 (NSD1) methyltransferase in coordinating lysine 36 methylation at histone 3 with RNA polymerase II function.

The NSD (nuclear receptor-binding SET domain protein) family encodes methyltransferases that are important in multiple aspects of development and disease. Perturbations in NSD family members can lead to Sotos syndrome and Wolf-Hirschhorn syndrome as well as cancers such as acute myeloid leukemia. Previous studies have implicated NSD1 (KMT3B) in transcription and methylation of histone H3 at lysine 36 (H3-K36), but its molecular mechanism in these processes remains largely unknown. Here we describe an NSD1 regulatory network in human cells. We show that NSD1 binds near various promoter elements and regulates multiple genes that appear to have a concerted role in various processes, such as cell growth/cancer, keratin biology, and bone morphogenesis. In particular, we show that NSD1 binding is concentrated upstream of gene targets such as the bone morphogenetic protein 4 (BMP4) and zinc finger protein 36 C3H type-like 1 (ZFP36L1/TPP). NSD1 regulates the levels of the various forms of methylation at H3-K36 primarily, but not exclusively, within the promoter proximal region occupied by NSD1. At BMP4 we find that this reduces the levels of RNAP II recruited to the promoter, suggesting a role for NSD1-dependent methylation in initiation. Interestingly, we also observe that the RNAP II molecules that lie within BMP4 have inappropriate persistence of serine-5 phosphorylation and reduced levels of serine-2 phosphorylation within the C-terminal domain (CTD) of the large subunit of RNAP II. Our findings indicate that NSD1 regulates RNAP II recruitment to BMP4, and failure to do so leads to reduced gene expression and abrogated levels of H3K36Me and CTD phosphorylation.

Whole-exome Sequencing in Penile Squamous Cell Carcinoma Uncovers Novel Prognostic Categorization and Drug Targets Similar to Head and Neck Squamous Cell Carcinoma.

PURPOSE: Penile squamous cell carcinoma (PSCC) is rare with limited treatment options. We report the first whole-exome sequencing (WES) analysis and compare the molecular landscape of PSCC with other squamous cell carcinomas (SCC), with the goal to identify common novel targets. EXPERIMENTAL DESIGN: PSCC and matched normal penile tissues from 34 prospectively followed patients, underwent genomic WES and human papilloma virus testing. We performed tumor mutation signature estimation by two methods, first to identify APOBEC-related mutation enrichments and second to classify PSCC-enriched mutational patterns based on their association with the Catalogue of Somatic Mutations in Cancer mutation signatures. We performed an extensive genomic comparison between our PSCC cohort and other SCCs in The Cancer Genome Atlas studies. RESULTS: We identified that most PSCC samples showed enrichment for Notch pathway (n = 24, 70.6%) alterations, comparable with head and neck squamous cell carcinoma (HNSC). PSCC mutation signatures are most comparable with HNSC signatures. PSCC samples showed an enrichment of two distinct mutational signatures, the first, associated with oncogenic activity of AID/APOBEC, and the second, associated with defective DNA mismatch repair and microsatellite instability. MP1 enrichment was positively correlated with increased tumor mutation burden (TMB; CC, 0.71; P < 0.0001) and correlated with significantly worse survival in comparison with those with the MP2 subset [HR, 10.2 (1.13-92.9); P = 0.039]. We show that a subset of PSCC (38%), with enrichment of APOBEC-related mutation signature, had significantly higher TMB and worse overall survival in comparison with non-APOBEC-enriched subset [HR, 2.41 (1.11-6.77); P = 0.042]. CONCLUSIONS: This study identified novel druggable targets and similarities in mutational signatures between PSCC and HNSC with potential clinical implications.See related commentary by McGregor and Sonpavde, p. 2375.

Evaluating the analytical validity of circulating tumor DNA sequencing assays for precision oncology.

Circulating tumor DNA (ctDNA) sequencing is being rapidly adopted in precision oncology, but the accuracy, sensitivity and reproducibility of ctDNA assays is poorly understood. Here we report the findings of a multi-site, cross-platform evaluation of the analytical performance of five industry-leading ctDNA assays. We evaluated each stage of the ctDNA sequencing workflow with simulations, synthetic DNA spike-in experiments and proficiency testing on standardized, cell-line-derived reference samples. Above 0.5% variant allele frequency, ctDNA mutations were detected with high sensitivity, precision and reproducibility by all five assays, whereas, below this limit, detection became unreliable and varied widely between assays, especially when input material was limited. Missed mutations (false negatives) were more common than erroneous candidates (false positives), indicating that the reliable sampling of rare ctDNA fragments is the key challenge for ctDNA assays. This comprehensive evaluation of the analytical performance of ctDNA assays serves to inform best practice guidelines and provides a resource for precision oncology.

Molecular Analysis of Clinically Defined Subsets of High-Grade Serous Ovarian Cancer.

The diversity and heterogeneity within high-grade serous ovarian cancer (HGSC), which is the most lethal gynecologic malignancy, is not well understood. Here, we perform comprehensive multi-platform omics analyses, including integrated analysis, and immune monitoring on primary and metastatic sites from highly clinically annotated HGSC samples based on a laparoscopic triage algorithm from patients who underwent complete gross resection (R0) or received neoadjuvant chemotherapy (NACT) with excellent or poor response. We identify significant distinct molecular abnormalities and cellular changes and immune cell repertoire alterations between the groups, including a higher rate of NF1 copy number loss, and reduced chromothripsis-like patterns, higher levels of strong-binding neoantigens, and a higher number of infiltrated T cells in the R0 versus the NACT groups.

Comprehensive T cell repertoire characterization of non-small cell lung cancer.

Immunotherapy targeting T cells is increasingly utilized to treat solid tumors including non-small cell lung cancer (NSCLC). This requires a better understanding of the T cells in the lungs of patients with NSCLC. Here, we report T cell repertoire analysis in a cohort of 236 early-stage NSCLC patients. T cell repertoire attributes are associated with clinicopathologic features, mutational and immune landscape. A considerable proportion of the most prevalent T cells in tumors are also prevalent in the uninvolved tumor-adjacent lungs and appear specific to shared background mutations or viral infections. Patients with higher T cell repertoire homology between the tumor and uninvolved tumor-adjacent lung, suggesting a less tumor-focused T cell response, exhibit inferior survival. These findings indicate that a concise understanding of antigens and T cells in NSCLC is needed to improve therapeutic efficacy and reduce toxicity with immunotherapy, particularly adoptive T cell therapy.

Use of Targeted Next-Generation Sequencing to Identify Activating Hot Spot Mutations in Cherry Angiomas.

Importance: Shared gene variants in benign-malignant process pairs, such as BRAF mutations common to benign nevi and melanoma, are associated with differing phenotypic manifestations. Study of gene mechanisms underlying cherry angioma may uncover previously unknown disease relationships. Objective: To identify somatic mutations present in cherry angioma specimens by using targeted next-generation sequencing. Design, Setting, and Participants: In a single-center case series, 10 formalin-fixed, paraffin-embedded cherry angioma specimens from biopsies performed at Massachusetts General Hospital in Boston from July 10, 2016, to January 23, 2018, were obtained and underwent sequencing across a panel of 323 genes most relevant to cancer. Somatic mutations were curated by excluding variants that were presumed to be germline or of low mapping quality. Main Outcomes and Measures: Identification of somatic mutations associated with cherry angiomas. Results: In 10 cherry angioma tissue samples originating from 6 female and 4 male patients with a median (range) age of 54 (26-79) years, 5 samples (50%) revealed somatic missense mutations in GNAQ (Q209H, Q209R, and R183G) and GNA11 (Q209H). Individually, these mutational hot spots are known to be involved in entities that include congenital and anastomosing hemangiomas, hepatic small-vessel neoplasms (Q209), port-wine stains, and Sturge-Weber syndrome (R183). Both hot spots are associated with blue nevi, melanoma associated with blue nevus, and uveal melanoma. Conclusions and Relevance: In this case series study, the high prevalence of 5 known genetic drivers within the benign cherry angioma entity appears to support the context-dependent role of gene alterations in both benign and malignant proliferations from various cellular origins.

Distinct Biological Types of Ocular Adnexal Sebaceous Carcinoma: HPV-Driven and Virus-Negative Tumors Arise through Nonoverlapping Molecular-Genetic Alterations.

PURPOSE: Ocular adnexal (OA) sebaceous carcinoma is an aggressive malignancy of the eyelid and ocular adnexa that frequently recurs and metastasizes, and effective therapies beyond surgical excision are lacking. There remains a critical need to define the molecular-genetic drivers of the disease to understand carcinomagenesis and progression and to devise novel treatment strategies. EXPERIMENTAL DESIGN: We present next-generation sequencing of a targeted panel of cancer-associated genes in 42 and whole transcriptome RNA sequencing from eight OA sebaceous carcinomas from 29 patients. RESULTS: We delineate two potentially distinct molecular-genetic subtypes of OA sebaceous carcinoma. The first is defined by somatic mutations impacting TP53 and/or RB1 [20/29 (70%) patients, including 10 patients whose primary tumors contained coexisting TP53 and RB1 mutations] with frequent concomitant mutations affecting NOTCH genes. These tumors arise in older patients and show frequent local recurrence. The second subtype [9/29 (31%) patients] lacks mutations affecting TP53, RB1, or NOTCH family members, but in 44% (4/9) of these tumors, RNA sequencing and in situ hybridization studies confirm transcriptionally active high-risk human papillomavirus. These tumors arise in younger patients and have not shown local recurrence. CONCLUSIONS: Together, our findings establish a potential molecular-genetic framework by which to understand the development and progression of OA sebaceous carcinoma and provide key molecular-genetic insights to direct the design of novel therapeutic interventions.

Correction: A feasibility study of returning clinically actionable somatic genomic alterations identified in a research laboratory.

[This corrects the article DOI: 10.18632/oncotarget.16018.].

Prospective Clinical Sequencing of Adult Glioma.

Malignant gliomas are a group of intracranial cancers associated with disproportionately high mortality and morbidity. Here, we report ultradeep targeted sequencing of a prospective cohort of 237 tumors from 234 patients consisting of both glioblastoma (GBM) and lower-grade glioma (LGG) using our customized gene panels. We identified 2,485 somatic mutations, including single-nucleotide substitutions and small indels, using a validated in-house protocol. Sixty-one percent of the mutations were contributed by 12 hypermutators. The hypermutators were enriched for recurrent tumors and had comparable outcome, and most were associated with temozolomide exposure. TP53 was the most frequently mutated gene in our cohort, followed by IDH1 and EGFR We detected at least one EGFR mutation in 23% of LGGs, which was significantly higher than 6% seen in The Cancer Genome Atlas, a pattern that can be partially explained by the different patient composition and sequencing depth. IDH hotspot mutations were found with higher frequencies in LGG (83%) and secondary GBM (77%) than primary GBM (9%). Multivariate analyses controlling for age, histology, and tumor grade confirm the prognostic value of IDH mutation. We predicted 1p/19q status using the panel sequencing data and received only modest performance by benchmarking the prediction to FISH results of 50 tumors. Targeted therapy based on the sequencing data resulted in three responders out of 14 participants. In conclusion, our study suggests ultradeep targeted sequencing can recapitulate previous findings and can be a useful approach in the clinical setting.

HIF1A is Overexpressed in Medulloblastoma and its Inhibition Reduces Proliferation and Increases EPAS1 and ATG16L1 Methylation.

BACKGROUND: Genetic and epigenetic modifications are closely related to tumor initiation and progression and can provide guidance for understanding tumor functioning, potentially leading to the discovery of new therapies. Studies have associated hypoxia-related genes to tumor progression and chemo/radioresistance in brain tumors. Information on the expression profile of hypoxiarelated genes in pediatric medulloblastoma, although scarce, may reveal relevant information that could support treatment decisions. OBJECTIVE: Our study focused on evaluation the of CA9, CA12, HIF1A, EPAS1, SCL2A1 and VEGF genes in 41 pediatric fresh-frozen medulloblastoma sample. Additionally, we analyzed the effect of hypoxia and normoxia in the pediatric medulloblastoma cell-line UW402. Furthermore, we assessed the effects of HIF1A knockdown in cell-proliferation and methylation levels of genes related to hypoxia, apoptosis and autophagy. METHOD: qPCR was performed to evaluate mRNA levels, and Western blot to confirm HIF1A silencing in both patient samples and cell line. Pyrosequencing was performed to asses the methylation levels after HIF1A knockdown in the UW402 cell line. RESULTS: A higher HIF1A mRNA level was observed in MB patients when compared to the cerebellum (non-tumor match). In UW402 MB cell-line, chemically induced hypoxic resulted in an increase of mRNA levels of HIF1A, VEGF, SCL2A1 and CA9 genes. Additionally, HIF1A knockdown induced a decrease in the expression of hypoxia related genes and a decrease of 30% in cell proliferation was also observed. Also, a significant increase in the methylation of ATG16L1 promoter and decrease in the methylation of EPAS1 promoter were observed after HIF1A knockdown. CONCLUSION: HIF1A knockdown in medulloblastoma cells lead to decreased cellular proliferation, suggesting that HIF1A can be a potential therapeutic target to be explored in the medulloblastoma. However, the mechanisms behind HIF1A protein stabilization and function are very complex and more data need to be generated to potentially use HIF1A as a therapeutical target.

Molecular determinants of post-mastectomy breast cancer recurrence.

Breast cancer (BC) adjuvant therapy after mastectomy in the setting of 1-3 positive lymph nodes has been controversial. This retrospective Translational Breast Cancer Research Consortium study evaluated molecular aberrations in primary cancers associated with locoregional recurrence (LRR) or distant metastasis (DM) compared to non-recurrent controls. We identified 115 HER2 negative, therapy naïve, T 1-3 and N 0-1 BC patients treated with mastectomy but no post-mastectomy radiotherapy. This included 32 LRR, 34 DM, and 49 controls. RNAseq was performed on primary tumors in 110 patients; with no difference in RNA profiles between patients with LRR, DM, or controls. DNA analysis on 57 primary tumors (17 LRR, 15 DM, and 25 controls) identified significantly more NF1 mutations and mitogen-activated protein kinase (MAPK) pathway gene mutations in patients with LRR (24%, 47%) and DM (27%, 40%) compared to controls (0%, 0%; p < 0.0001 and p = 0.0070, respectively). Three patients had matched primary vs. LRR samples, one patient had a gain of a NF1 mutation in the LRR. There was no significant difference between the groups for PTEN loss or cleaved caspase 3 expression. The mean percentage Ki 67 labeling index was higher in patients with LRR (29.2%) and DM (26%) vs. controls (14%, p = 0.0045). In summary, mutations in the MAPK pathway, specifically NF1, were associated with both LRR and DM, suggesting that alterations in MAPK signaling are associated with a more aggressive tumor phenotype. Validation of these associations in tissues from randomized trials may support targeted therapy to reduce breast cancer recurrence.

Survival Outcomes by TP53 Mutation Status in Metastatic Breast Cancer.

PURPOSE: We sought to determine the significant genomic alterations in patients with metastatic breast cancer (MBC), and survival outcomes in common genotypes. PATIENTS AND METHODS: High-depth next generation sequencing was performed for 202 genes in tumor and normal DNA from 257 patients with MBC, including 165 patients with ER/PR+ HER2- (hormone receptor positive, HR+ positive), 32 patients with HER2+ and 60 patients with triple negative (ER/PR/HER2-) cancer. Kaplan Meier survival analysis was performed in our discovery set, in breast cancer patients analyzed in The Cancer Genome Atlas, and in a separate cohort of 98 patients with MBC who underwent clinical genomic testing. RESULTS: Significantly mutated genes (SMGs) varied by histology and tumor subtype, but TP53 was a SMG in all three subtypes. The most SMGs in HR+ patients included PIK3CA (32%), TP53 (29%), GATA3 (15%), CDH1 (8%), MAP3K1 (8%), PTEN (5%), TGFBR2 (4%), AKT1 (4%), and MAP2K4 (4%). TP53 mutations were associated with shorter recurrence-free survival (P=0.004), progression-free survival (P=0.00057) and overall survival (P=0.003). Further, TP53 status was prognostic among HR+ patients with PIK3CA mutations. TP53 mutations were also associated with poorer overall survival in the 442 HR+ breast cancer patients in the TCGA (P=0.042) and in an independent set of 96 HR+ MBC who underwent clinical sequencing (P=0.0004). CONCLUSIONS: SMGs differ by tumor subtype but TP53 is significantly mutated in all three breast cancer subtypes. TP53 mutations are associated with poor prognosis in HR+ breast cancer. TP53 mutations should be considered in the design and interpretation of precision oncology trials.